Local jails are driving the steady flow of incarcerated people in this country. Much is made of non-violent offenders serving long sentences in federal prison, or how mandatory minimum sentences are clogging America’s prisons. The fact is, one-third of all inmates are held in local jails.

The difference between a jail and a prison is simple. Jails are run by local government bodies for short-sentences, often the result of minor offenses, and pre-trial detention. Prisons are for long sentences, for serious crimes and operated by states or the federal government.

According to a new study released by the Prison Policy Institute, the 11 million people who go to jail each year are there for brief, but life-altering, periods of time. Most are released in days, or hours, after their arrest, but others are held for months or more. Only one in three people in jails have been convicted.

I have used this column to lament the ridiculousness of detaining people who cannot afford minimal bail. Those people sit in jail for months only to have the charges dismissed or are released for time served -- often after serving much longer sentences than would have been meted out if a plea agreement had been negotiated sooner.

Beyond bail there are an increasing number of jails that run a side-business of renting jail cells to other government agencies. The jail is looked at in some communities as a money maker. For one, it employs local residents and that employment helps churn residual businesses in the community. In addition, county officials charge a fee for out-of-county or out-of-state inmates and even immigration detainees.

That money is used to balance local budgets. In more than half of U.S. states, about 10 percent of the people in jail are not “traditional jail inmates.” They are people being held under contract for federal or state agencies. According to the Prison Policy Initiative, the systematic renting of jail cells to other jurisdictions has changed the priorities and the policies of jail officials. If the county is making money, an overcrowded jail is not a bad thing.

In Pennsylvania, state prisoners who violate their parole are not immediately returned to state prison. Due to some creative legislation, parole violators are housed in county jails for up to 6 months and then returned to the community. The state pays the county to house the parole violators and in turn the state can boast that they have less men and women in state prisons. Mind you, not less prisoners, but less prisoners in state facilities.

The problem goes beyond Pennsylvania. States like Alabama, Kansas, Kentucky, Mississippi, New Jersey, New Mexico, North Dakota, Tennessee and Utah are in the business of renting space to federal authorities.

Louisiana has mastered the “for profit public prison.” According to the Prison Policy Institute, Louisiana has largely outsourced the construction and operation of state prisons to individual parishes. Fifty-two percent of the state’s prison population is housed under contract with local jails; and as a result two out of three people held in Louisiana jails are not “traditional jail inmates.”

The federal government is gobbling up local jail cells as well. According to the Prison Policy Initiative, the U.S. Marshals Service rents about 26,200 cells each year, mostly to hold federal pre-trial detainees in locations where there is no federal detention center. Immigration and Customs Enforcement also rents about 15,700 cells each year for people facing deportation.

If filling local jails becomes a cash cow for local municipalities, the future is predictable and terrifying. Local government officials have a financial incentive to fill their jails -- regardless of the toll on communities, families and individuals.

-- Matthew T. Mangino is of counsel with Luxenberg, Garbett, Kelly & George P.C. His book “The Executioner’s Toll, 2010” was released by McFarland Publishing. You can reach him at www.mattmangino.com and follow him on Twitter at @MatthewTMangino.